﻿#include<iostream>
using namespace std;
int main()
{
    double x;
    cin >> x;
    double l = -10000, r = 10000;
    while (r - l > 1e-8)
    {
        double mid = (l + r) / 2;
        if (mid * mid * mid >= x) r = mid;
        else l = mid;
    }
    printf("%.6lf",l); //lf表示是double型，f表示float，.6表示小数点后6位
    system("pause");
    return 0;
};